The present invention relates to a system for monitoring the operation of input transducers of a central control and monitoring unit for machines and/or devices usable in the production and/or product packaging lines, for example production lines for cigarettes and/or lines for packaging packets of cigarettes. Such lines can for example include cigarette-making machines, filter fitters, packaging machines, cellophaning machines, cartonising and parcelling machines. As is known, such individual machines or production lines are controlled by a central control and monitoring unit, which in dependence on determined signals emitted by input transducers, determines the operation of various output transducers, at suitable instances, such output transducers belonging also to different machines in the same lines.